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A pulsed-power generator with high current rise based on a pulse-forming-network was studied toward generating intense point-spot X-ray source. To obtain the high rate of current rise, we have designed the compact discharge device with low circuit inductance. The results indicate that the inductance of the compact discharge device was dominated by a gap switch inductance. To reduce the gap switch inductance and operation voltage, the feasible gap switch inductance in the vacuum chamber has been estimated by the circuit simulation. The gap switch inductance can be reduced by the lower pressure operation. It means that the designed discharge device achieves the rate of current rise of 10 12 A/s.

Summary form only given. For observing interior of dense plasmas, intense, point-spot X-ray source is generated by X-pinch technique1. Required parameter of the pulse generator is the rate of current rise 1012 A/s, i.e. 100 kA of current and 100 ns of current rising time2.To generate X-ray source by using X-pinch system, PFN module3 was used, having the advantages of holding high peak current, simple fabrication, and so on. The circuit topology of the PFN module through circuit simulations has been optimized, and three-stage LC-ladder of PFN is suitable for the table-top power supply for X-pinch. The inductance component included in the generator is strongly affected to the rate of current rise. In order to reduce the inductance of the X-pinch system, we evaluate the inductance and the rate of rise, experimentally. The PFN modules were coaxially arranged in octagon plates, and 48 PFN modules can be connected to drive the X-pinch. The PFN module consists of a three-stage LC-ladder circuit, which 73 nH of the inductance and 2700 pF of the capacitance. The discharge device has a coaxial configuration to reduce the inductance. The load current flowing through the inductance measured using a Rogowski coil, contained in the device was determined by comparison between the calculated results with Alternative Transients Program-Electromagnetic Transients Program (ATP-EMTP)4. The rate of current rise obtained was 1.7 x 1011 A/s. From these experiments, the electrode inductance of 65 nH was estimated from the results calculated by the ATP-EMTP. The charging voltage to achieve the target rate of current rise is evaluated to be about 60 - 80 kV.

A pulsed-power generator with a high rate of current rise was studied toward generating intense X-ray source from an X-pinch plasmas. The pulsed-power generator consists of 48 pulse-forming-network (PFN) modules with a three-stage of LC ladder circuit. To evaluate the rate of current rise for the pulsed-power generator, we demonstrated the short circuit experiments with low operation voltage. The rate of current rise depends on the number of PFN modules due to the decrease of inductance of PFN. The rate of current rise for 48 PFN modules at 10 kV of an operation voltage is estimated to be 0.1 kA/ns. To predict the rate of current rise for the requirement to obtain the intense X-ray from the X-pinch, the circuit simulation was demonstrated. The results indicated that the operation voltage requires over 70 kV for the rate of current rise of 1 kA/ns.

虚血性心疾患の終末像ともいえる虚血性心筋症は,慢性的うっ血性心不全を呈し,内科的治療では予後不良である.本症は特発性あるいは他の二次性心筋症とは異なり外科治療の可能性を秘めている.したがって,その発生前の早期診断,早期治療の重要性はいうまでもないが,正確な診断と手術適応の決定は予後に大きな影響をもたらす.われわれは68歳男性でNYHA IV度の重症左心機能低下例で虚血性心筋症としての病像を呈した症例に対してA-Cバイパス術を行い,臨床症状の著明な改善を得た.術前の左室拡張末期圧は30mmHg,左室拡張末期容量は281.8cc/m2,左室駆出率は13.1%であった.虚血性心筋症においては心筋のviabilityのある有意冠動脈病変には積極的な血行再建術を行うべきである.

A right thrombus was incidentally found in a 65-year-old male during mitral valve surgery. A mushroom-like thrombus was attached to the inferior limb of the fossa ovalis with broad based stalk. It developed in sinus rhythm and in the absence of evidence of blood stasis in the right atrium. The most likely pathogenesis of right atrial thrombus formation in this case is endocardial damage from right heart catheterization prior to surgery.

We observed a case of severe intravascular haemolysis following repair of subpulmonaic ventricular septal defect with pulmonic stenosis. In this case immunological studies and cardiac catheterization demonstrated haemolysis resulting from mechanical factors. When severe haemolysis and progressive anemia following intracardiac repair persists, inadequate intracardiac correction should be suspected and the second surgery is to be considered.

A case with an exceptional form of congenitally bicuspid aortic valve is described. A fibrous strand connected to the supra-aortic ridge supported the conjoined cusp, and severe pure aortic regurgitation was present although the fibrous strand remained intact. Aortic valve replacement was successfully performed.

The case is reported of a 38-year-old housewife with a common atrium associated with anomalous high insertion of the inferior vena cava, absence of the coronary sinus, and drainage of a left hepatic vein into the left side of common atrium. Surgical repair was performed successfully. The procedure was closure of a nearly total atrial septal defect with a Dacron patch. Embroyologically, the development failure of the sinu-atrial fold appears to be the basic causal factor.

We have seen a case of rupture of an aneurysm of the noncoronary sinus into the right atrium. Surgery revealed an aneurysmal mass the size of the tip of an index finger extending through the inter-atrial septum down to just above the tricuspid valvular ostium. An electrocardiogram showed first-degree atrioventricular block, while the His bundle electrogram demonstrated the presence of disturbances in the intra-atrial as well as His bundle conduction. The disturbance in His bundle conduction was interpreted as being due to compression of the His bundle by the aneurysm.

We report a patient with ruptured aneurysm of the aortic sinus of Valsalva into the right ventricle, whose heart murmur represented only a diastolic element without aortic regurgitation. Surgery revealed a small opening through myocardium of the ventricular septum without ventricular septal defect. During systole, the opening was constricted and presumably closed with myocardial contraction, and left-to-right shunt might have occurred only in diastole. This might lead to only a diastolic murmur.

A 26-year-old woman with partial anomalous pulmonary venous drainage into the right atrium (Scimitar syndrome) was successfully operated upon by incorporating an intra-atrial conduit. The single right pulmonary vein present was connected to the right atrial inferior vena cava junction. The atrial septum was extremely deviated to the left, and the left atrium was located entirely on the left of the spine. A small patent foramen ovale was found. The distance between the orifice of the right pulmonary vein and the enlarged atrial septal defect was too great to use an intracardiac patch, so a 14 mm woven Dacron graft, 6 cm long, was interposed between them. The patient is doing well 21 months following the operation.

Duplication of the mitral valve is a rare congenital cardiac anomaly .We encountered a case of duplication of the mitral valve associated with a partial form of endocardial cushion defect in a 6-year-old girl. The mitral orifice was separated by a fibrous tissue and each orifice provided papillary muscle and complete subvalvular mechanisms except for the cleft region. The fibrous tissue also provided a subvalvular apparatus. The cleft region. The fibrous tissue also provided a subvalvular apparatus. The cleft was repaired without complication. The short axis view of the two-dimmensional echocardiogram demonstrated two separate holes in the mitral valve, which constituted the most obvious diagnostic sign prior to surgery.

An anomalous origin of the left coronary artery from the pulmonary artery in a 26-year-old man was corrected by the ligation of the artery at its anomalous origin, followed by the construction of an aortocoronary bypass with a venous graft. The flow of blood to the myocardium was measured for the purpose of comparing the effect of the bypass method with that of the ligation method. The result suggested that the bypass method provided a greater flow of blood to the myocardium than did ligation alone.